Free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A levels – late markers of abnormal implantation and placentation. Comparison between spontaneous and IVF singleton pregnancies

Abstract

Background. During the late first trimester, between 11-13 weeks of gestation, it is recommended for all pregnant women to have a screening for Down syndrome and for other chromosomal abnormalities like trisomy 13 or 18, because it estimates the potential risk and allows patients to make an informed choice about the continuation of pregnancy. The combined test analyzes three markers along with the maternal age: maternal serum beta-human chorionic gonadotropin (beta-hCG or free beta-hCG subunit), maternal serum pregnancy-associated plasma protein-A (PAPP-A) and an ultrasound measurement of nuchal translucency (NT). Objectives. To determine if there are differences regarding serum markers and pregnancy outcomes between spontaneous pregnancies and pregnancies obtained by assisted reproductive techniques (ART). Materials and method. We performed a literature review by searching MEDLINE and Cochrane databases using the keywords: beta-hCG, PAPP-A, screening, IVF, ICSI, ART, implantation. Results. Assisted reproduction techniques, such as in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), can alter serum markers levels and mimic the pattern associated with Down syndrome: maternal serum beta-hCG and inhibin A levels tend to be increased, while estradiol and PAPP-A levels are decreased. When comparing spontaneously conceived (SC) singleton pregnancies with in vitro fertilization/intracytoplasmic sperm injection, cohort studies confirm an increased risk of perinatal complications for the latter. The most frequent adverse outcomes are: preterm birth, intrauterine growth restriction, perinatal mortality, congenital malformations and higher risks for preeclampsia and placenta praevia. Conclusions. Overall, the risk of complications is significantly higher in ART pregnancies, but the reasons for this increase are still uncertain. The possible cause of this difference might be the increased maternal age and the particularities that occur during the implantation and placentation.